Exception in thread main Java

This is my program to print natural numbers from 1 to N^2 in a clockwise spiral. I’m getting the following error

     Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: Index -2147483648 
out of bounds for length 3
    at Spiral.main(Spiral.java:13)

This is my program

class Spiral{
   public static void main(String[] args) {
       System.out.println("Enter value of N"); 
       Scanner sc=new Scanner(System.in);
       int N=sc.nextInt();
       int arr[][]=new int[N][N];
       int r1=0, c1=0, r2=N-1, c2=N-1, flag=1; int i=0,j=0;
       while(flag<=N*N)
      { for(j=c1;j<=c2;j++)
       arr[r1][j]=flag++;
       
       
       for( i=r1+1;i<=r2;i++)
        arr[i][c2]=flag++;  //this is the line of error
       
       
       for(j=c2-1;j>=c1;j--)
        arr[r2][j]=flag++;
       
       
       for(i=r2-1; i>r1+1;i--)
        arr[i][c1]=flag++;
       
       
       r1++; r2--; c1++; c2--; 
      }
       System.out.println("The Circular Matrix is:");
for( i=0;i<N;i++)
{
for( j=0;j<N;j++)
{
System.out.print(arr[i][j]+ "t");
}
System.out.println();
} 
}
}

The code works fine for N=2 but starts giving this error for N=3,4 etc. If N=3, the greatest value of arr[i][c2] will be arr[2][2] which falls in the range of a 3×3 matrix. Could someone explain why I’m getting this error then?

Answer

Increment/decrement r1, c2, r2, and c1 appropriately after their corresponding for loops rather than at the end of the while loop:

import java.util.Scanner;

class Spiral {

    public static void main(String[] args) {
        System.out.println("Enter value of N");
        Scanner sc = new Scanner(System.in);
        int N = sc.nextInt();
        int[][] arr = new int[N][N];
        int r1 = 0, c1 = 0, r2 = N - 1, c2 = N - 1, flag = 1;
        int i = 0, j = 0;
        while (flag <= N * N) {
            for (j = c1; j <= c2; j++)
                arr[r1][j] = flag++;
            r1++;
            for (i = r1; i <= r2; i++)
                arr[i][c2] = flag++;
            c2--;
            for (j = c2; j >= c1; j--)
                arr[r2][j] = flag++;
            r2--;
            for (i = r2; i >= r1; i--)
                arr[i][c1] = flag++;
            c1++;
        }
        System.out.println("The Circular Matrix is:");
        for (i = 0; i < N; i++) {
            for (j = 0; j < N; j++) {
                System.out.print(arr[i][j] + "t");
            }
            System.out.println();
        }
    }

}

Example Usage 1:

Enter value of N
4
The Circular Matrix is:
1   2   3   4   
12  13  14  5   
11  16  15  6   
10  9   8   7   

Example Usage 2:

Enter value of N
7
The Circular Matrix is:
1   2   3   4   5   6   7   
24  25  26  27  28  29  8   
23  40  41  42  43  30  9   
22  39  48  49  44  31  10  
21  38  47  46  45  32  11  
20  37  36  35  34  33  12  
19  18  17  16  15  14  13